Injection needle devices and systems are used to inject a medicant into a tissue site of a patient. One current style of injection needle device uses a plurality of needles, for example three (3). When the desired number of injection sites into the tissue is greater than the number of needles provided as part of the injection needle device, multiple injection cycles must be performed. In order to perform a second injection cycle with the device, it is necessary to turn, rotate or reposition the device so that the needles of the device are aligned with additional tissue sites which are intended to receive an injection of the medicant. This repositioning requires that the extended or deployed needles first be retracted or withdrawn so as not to extend from the tip of the device and then, depending on the tissue site, the tip of the device may have to be partially retracted in order to be turned and repositioned before the needles are once again deployed (i.e. extended from the tip) for injection of the medicant into other tissue sites.
The tip of the injection device which is intended to be positioned adjacent the tissue site, includes an array of apertures which receive the injection needles. A mechanical deployment structure is used to extend the pointed and open tips of the needles (one (1) needle per aperture) for the injection of medicant and in order to retract the tips of the needles when the device is not in use and/or when the device is being repositioned for a second or subsequent injection cycle.
In one example of an earlier injection device, there are three (3) injection needles and the selected injection procedure includes nine (9) desired tissue injection sites. A specific use of this earlier device would be for the injection of autologous derived cells into the urinary sphincter of a patient for the treatment of stress urinary incontinence (SUI). In order to deliver medicant to each of the nine (9) tissue injection sites, three (3) injection cycles must be performed. A degree of precision in the positioning and orientation of the device is required and the desired degree of precision is difficult to exercise. The tip of the device is held at the meatus of the sphincter while extending (i.e. deploying) the three (3) injection needles into the tissue. A delivery syringe in cooperation with a common manifold is used for delivering medicant from that common manifold to each of the three (3) injection needles. Assuming that the common manifold initially contains all of the medicant for the nine (9) tissue sites, it becomes important that manipulation of the delivery syringe be used in such a way that its plunger is only depressed approximately one-third (⅓) of its total travel in order to deliver the desired or correct dosage (approximately one-third) of cell-based treatment (i.e. the medicant) as part of the first injection cycle. This constitutes the first cycle of three (3) and is completed when the three (3) needles are withdrawn into the tip of the device so that the device can be repositioned for the second injection cycle to be performed. Part of the repositioning of the device for the second cycle requires that the device be rotated so as to reposition the three (3) needles, actually the three (3) needle apertures since the needle tips have been retracted, to the desired location of three (3) new tissue sites for the next three (3) injections into those sites. At this second position for the second injection cycle, the three (3) needles of the device are extended or deployed into the tissue and the common syringe plunger is depressed another one-third (⅓) of its travel into the common manifold. This is intended to deliver the second one-third (⅓) of the medicant at these three (3) new tissue sites. Six (6) of the nine (9) selected injection sites have now received an injection of the medicant, presumably the scheduled dosage of the medicant. The third and final cycle is essentially a repeat of the second cycle. This third cycle begins when the device is rotated to the position where the three (3) needle apertures are aligned with the final three (3) injection sites. The needles are then deployed for medicant injections into the final three (3) tissue sites.
One of the concerns with the type of injection device which has been described is that it uses a separate syringe which is suspended from a luer connection at its proximal end. This assembly approach presents a concern regarding the structural integrity of the connection. A further concern with this type of earlier injection device, as described, is the use of a manifold to flow couple the three (3) needles to be syringe. The use of a manifold in this context may introduce turbulence and an inconsistent distribution of the medicant. Another concern is the use of a separate syringe and the inability to purge air from the system. Further, with the need for and use of long needle cannulas, the volume of the cannulas becomes a concern.
The type of injection device which has been described as being representative of some earlier constructions, includes a manifold or reservoir for the medicant and the manifold is either directly or indirectly connected to each of the three (3) needles which are arranged in parallel. A single plunger is cooperatively arranged with the manifold for pushing the medicant into and through each needle. If one tissue site is more dense than another tissue site, the amount of medicant which is injected at each site will not be equal. If individual syringe barrels are associated with each needle and if each barrel has its own cooperating plunger and piston, then this inequality problem in medicant distribution among the selected tissue sites would be solved. This is the selected structure which is disclosed herein in the exemplary embodiment.
The various design issues and concerns which are outlined above are the focus of the embodiments of the present disclosure. The preferred embodiment incorporates a multi-barrel syringe and a needle count which corresponds to the number of desired tissue injection sites for the particular treatment. Cooperating elements and structures of the multi-barrel syringe provide other design features which are considered to be novel and unobvious relative to the current state of the art.